M6: 1.76.err
Release Notes
There is no reason to install this update if you're playing Classic WoW. I do not recommend installing this update if you're playing Modern WoW.
It can, however, be loaded on the Modern 12.0.0 client by checking the "Load out of date AddOns" checkbox in the in-game AddOn List. If you interact with M6 while in combat, in instances, in PvP, or use certain advanced features, you will likely encounter incorrect in-game behavior and errors, and may lose your saved M6 macros or settings. Please back up your World of Warcraft/_retail_/WTF folder before loading this.
Proper support for patch 12.0.0 is planned for a future M6 update. It is, unfortunately, not just a matter of "updating the .toc file."